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So now we're in the fourth layer of the U.S. reference model, the transport layer, welcome to the

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layer of TCP.

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The transport layer is the level at which system reliability and quality are ensured.

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The basic function of the transport layer is to accept data from the layer above.

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Split it up into smaller units.

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Past these data units to the network layer.

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And ensure that all the pieces arrive correctly at the other end.

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OK, so now let's look at the functions of the transport layer in detail.

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Service point addressing.

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Transport layer header includes service point address, which is the port address, this layer gets

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the message to the correct process on the computer, unlike network layer, which gets each packet to

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the correct computer.

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Segmentation and reassembling.

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A message is divided into segments.

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Now, each segment contains a sequence number which enables this layer to reassemble the message.

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The message is reassembled correctly upon arrival at the destination and replaces packet's which were

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lost in transmission.

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Connection, control.

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It includes two types, Conexion, less transport layer, each segment is considered as an independent

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packet and delivered to the transport layer at the destination machine.

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Connection oriented transport layer.

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Before delivering packets, connection is made with the transport layer at the destination machine.

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Flow control.

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And this layer flow control is performed and duen.

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The rate of data transmission between two nodes must sometimes be managed to prevent a fast sender from

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transmitting more data than can be supported by the receiving data buffer causing a buffer overrun.

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And we don't want that.

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Air control, air control is performed end to end in this layer to ensure that the complete message

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arrives at the receiving transport layer without any air.

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Error correction is done through retransmission.

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On the Internet, TCP and UDP provide the services for most applications.

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Coming up next, we'll look at all the other details of the transport layer under TCP and UDP topics.